ALTIM

Format

Parameters

destination
ADDE point dataset name and absolute position; specify as group/descriptor.position or alias.position;
only positive integers are valid for position

time

observation
time (default=0 if current time is between 0 UTC and 11:59 UTC, otherwise
default=12)

day

observation
date; valid formats include YYYYDDD, YYYY/MM/DD and DD/MON/YYYY where
YYYY, DDD, MM and DD are integers and MON is three or more letters, e.g.,
JAN or JANUARY (default=current)

Keywords

COuntry=

c1
. . cN

calculate
and write data for soundings in these countries; specify up to six countries
using their two-letter codes; use the CCODE command
to list valid codes; see the Remarks (default=all countries)

DATaset=

mand sig

source
ADDE point dataset names for mandatory- and significant-level data; specify
as group/descriptor or alias; you must specify NONE
in the sig parameter or SIG=NO keyword to use only mandatory
data, i.e., ignore the significant data (mand default=RTPTSRC/UPPERMAND; sig default=RTPTSRC/UPPERSIG
if mand=RTPTSRC/UPPERMAND, otherwise sig default=NONE)

DELete=

YES

delete
the destination file before copying

NO

do
not delete the destination file before copying (default)

LAT=

slat nlat

calculate
and write data for soundings in this latitude range, where slat and nlat are
the southern and northern latitude limits, respectively; see the Remarks
(default= –90 90)

LON=

elon
wlon

calculate
and write data for soundings in this longitude range, where elon and wlon are
the eastern and western longitude limits, respectively; see the Remarks
(default= –180 180)

OPTion=

H

calculate
and write data at heights from 0 to 45,000 feet at 1,000 foot increments;
see the Remarks (default)

P

calculate
and write data at standard pressures from 18,000 to 45,000 feet at 1,000
foot increments

SIG=

YES

include
data from the significant-level dataset specified in the DATASET keyword
(default)

NO

do
not include data from the significant-level dataset specified in the
DATASET keyword; use only its mandatory-level dataset

STate=

s1
. . sN

calculate
and write data for soundings in these states; specify up to six states
using their two-letter state Post Office abbreviations; see the Remarks
(default=all states)

TITLE=

'text'

title
of the destination point file; must be 32 characters or less (default=Altimeter
Interpolation: yyyyddd); yyyyddd in the default is
the date of the source dataset

Remarks

ALTIM reads
data from the source upper-air dataset and interpolates the values to standard
aviation heights or pressures, then writes the data to the destination dataset
(an IHGT schema MD file). The IHGT schema must be registered with command SCHE DCIHGT
before you use this command. If the specified destination file already exists,
you must delete it with DEL=YES since ALTIM cannot append data to an existing
file.

Because of
the large number of calculations performed for each sounding, ALTIM may take
a long time to complete. You can minimize this time and the number of soundings
by specifying only the needed data with the LAT and LON, COUNTRY or STATE keywords.

Standard
pressures, as specified with OPT=P, are the pressures of the standard atmosphere
from 18,000 feet to 45,000 in 1000 foot increments (i.e., 18000, 19000, 20000,
etc.). Use OPT=P to calculate the data at these "standard atmosphere" pressures.
Use OPT=H to calculate the data at heights from 0 to 45,000 feet at 1000 foot
increments, using the heights in the source dataset (converted to thousands
of feet), not the standard atmosphere pressure model.

Examples:

ALTIM LOCAL/AVIATION.10 0

This entry
calculates upper-air data from 0 to 45,000 feet at 1000 foot increments using
today's 0 UTC data in the default source datasets RTPTSRC/UPPERMAND and RTPTSRC/UPPERSIG.
The data is written to position 10 of dataset LOCAL/AVIATION, an IHGT-schema
point file.

This entry
calculates upper-air data at standard pressures from 18,000 to 45,000 feet
at 1000 foot increments for the state of Florida. It uses today's 12 UTC data
in the default datasets RTPTSRC/UPPERMAND and RTPTSRC/UPPERSIG. The data is
written to position 10 of dataset LOCAL/AVIATION, an IHGT-schema point file.
The DEL=YES and TITLE keywords delete the existing destination point file and
create a new one with the title 12 UTC IHGT data for Florida.